Angiogenesis is the process of new blood vessel development from preexisting vasculature. Angiogenesis is a normal process in growth and development, as well as in wound healing. Vasculogenesis is the process of blood vessel formation from endothelial progenitor cells (EPC) that differentiate in situ.
Until recently, vasculogenesis was thought to be limited to embryologic development. However, the discovery of circulating endothelial progenitor cells has provided evidence that postnatal vasculogenesis also occurs in adults. Neovascular growth, including angiogenesis and vasculogenesis, can contribute to various disease states, including many cancers (Rafii et al. (2002) Nature Reviews Cancer 2(11):826-835). New tumor-associated blood vessels provide blood flow that allows for the further growth of the tumor and provide a pathway by which tumor cells can metastasize.
The ability to target vasculature for imaging (e.g., for diagnosing or monitoring cancer) or drug delivery purposes has been an elusive goal. Therefore, novel methods and compositions for targeting sites of neovascular growth are needed.